1. Field of the Invention
The present invention relates in general to sockets for interconnecting torque tools and fastening elements and, more specifically, to an assembly intercalated between a torque tool and a fastening element, for measuring torques and tightening angles.
2. Description of the Prior Art
In fastening operations, it is often required to tighten a threaded fastener until it is adequately tensioned, thereby insuring that the latter securely holds the work piece. In order to install threaded fasteners, such as screws, bolts, nuts or the like, a tool is used to apply the required torque or tension. In critical applications, the installing tool apparatus does not have the means of measurement, is incapable of accurately measuring the require tension, or it is required that a secondary measurement device be used to verify that the required tension has been achieved.
There are several accepted methods for measuring the applied tension in threaded fasteners. In one method, the required tension is determined by applied torque, which is previously established by engineering calculus. According to this method, the torque, or torsional load is often measured using strain gauge(s). According to another method, the required tension is measured by an angular displacement of a fastener. Attempts have been made to develop an apparatus, using various ultrasonic techniques, for directly measuring fasteners tension. For example, U.S. Pat. No. 5,058,439 granted on Oct. 22, 1991 to Carpenter for a “UT Socket Assembly” discloses an ultrasonic transducer socket assembly, used with a torque tool, for simultaneously tightening a bolt and measuring bolt load. A pole adaptor rigidly attached to a driving socket for engaging and driving a bolt has a stationary cylinder mounted therein. A second cylinder, rotatable and slidably received in the stationary cylinder, has an ultrasonic transducer pivotally mounted at one end that contacts the bolt to be tightened, when the socket is engaged with the bolt. The rotating cylinder and transducer are rotated approximately 180 degrees during engagement of the socket and bolt to smear an even couplant layer between the bolt and transducer to assure consistent measurements of bolt load during tightening a socket assembly including a ultrasonic transducer capable of measuring the bolt tension.
Although directly measuring bolt tension is advantageous, the foregoing apparatus has several disadvantages. Among them, the fact that the apparatus incorporates complex mechanical features which can negatively affect the precision of the measurements, increases the manufacturing cost, reduces the reliability, and greatly increases the length and weight of the socket which in many applications is impractical.